code: def _objective_function_prox_tvl1(
      input_img, output_img, gradient, weight
  ):
      diff = (input_img - output_img).ravel()
      return 0.5 * (diff * diff).sum() + weight * tv_l1_from_gradient(
          gradient
      )
  
file_path: nilearn/nilearn/decoding/_proximal_operators.py
imports: from math import sqrt
  import numpy
  from ._objective_functions import divergence_id, gradient_id, tv_l1_from_gradient
label_desc: Use image node_id 5 for calling a global function with example usage: _objective_function_prox_tvl1(input_img, output_img, gradient, weight) and returns: unknown